Always call PotionSplashEvent. Fixes BUKKIT-3363

This change allows plugins to add recipients to a PotionSplashEvent
when it would have otherwise had none.
Improve the item meta deserialization code-style

Fixed the ItemMetaFireworkTest

Add set power unit tests for FireworkMeta
Add BlockEnderPortal for diff visibility
[Bleeding] Add experimental support for entity portal traveling
Fix broken null contract with Jukebox.setPlaying, Fixes BUKKIT-3429

The javadocs state that a null may be used to remove the currently
playing sound, however this causes a NullPointerException.

It also doesn't process registering the record correctly, along with
processing non-valid items.
Refactor processBlockPlace logic. Fixes BUKKIT-3406 and BUKKIT-3454

The previous logic was faulty since it lost the logic of "placing" the
block. It was also taking into account data that could have been
changed outside of the processing of this event, which is irrelevant
to the processing of this event.